The Echinoid Directory

Prionocidaris Agassiz, 1863, p. 18

[=Stephanocidaris Agassiz, 1872, p. 160, type species Stephanocidaris bispinosa Agassiz, non Lamarck, 1816 [=Phyllacanthus australis Ramsay, 1885; = Schleinitzia Studer, 1876, p. 862, type species Schleinitzia crenularis Studer [=Cidarites bispinosa Lamarck, 1816]; =Pleurocidaris Pomel, 1883, p. 111, type species Rhabdocidaris subvenulosa Peron & Gauthier, 1880; =Actinocidaris Mortensen, 1928, p. 73, type species Phyllacanthus thomasi Agassiz & Clark, 1907 ]

Diagnostic Features
  • Test relatively tall; moderately thin and fragile.
  • Apical disc 40-50% test diameter; monocyclic. Genital plates all similar in size. All plates covered in scattered tubercles.
  • Interambulacra with up to 12 plates in a series. Primary tubercles perforate and non-crenulate (the most adapical tubercles may have a trace of crenulation on their adapical side). Areoles ovate; incised; separated by scrobicular circles except immediately beside the peristome.
  • Scrobicular tubercles hardly differentiated. Extrascrobicular zones not extensive; densely covered in heterogeneous secondary tubercles and granules.
  • No sutural pits or furrows.
  • Ambulacra weakly sinuous. Pore zones not incised; pore-pairs subconjugate to conjugate, the two pores usually widely separated. Perradial zone fully tuberculate, with marginal series of contiguous primary tubercles and inner zone of smaller secondary tubercles.
  • Peristome a little smaller than apical disc. Interradial plate series not quite reaching the peristome; ambulacral plates uniserial in each column.
  • Primary spines long and relatively slender; tapering or ending in small crown. Collar and neck short; shaft ornamented in rows of modest thorns; surface between thorns covered in fine cortical hairs.
  • Secondary spines flattened but not adpressed.
Lower Cretaceous (Albian) to Recent, worldwide.
Name gender feminine
Cidarites pistillaris Lamarck, 1816, p. 55, by original designation.
Species Included
  • P. baculosa (Lamarck, 1816); Recent, Indo-Pacific.
  • P. pistillaris (Lamarck, 1816); Recent, Indian Ocean.
  • P. australis (Ramsay, 1885); Recent, Australia.
  • P. popiae Hoggett & Rowe, 1986; Recent, New Caledonia.
  • P. callista Rowe & Hoggett, 1986; Recent, New South Wales, Australia.
  • P. glandulosa (de Meijere, 1904); Recent, Indo-West Pacific.
  • P. hawaiiensis (Agassiz & Clark, 1907); Recent, Hawaii.
  • P. thomasi (Agassiz & Clark, 1907); Recent, Hawaii.
  • P. bispinosa (Lamarck, 1816); Recent, Indo-West Pacific.
  • many fossil species, including:
  • P. neglecta Smith & Wright, 1989; Upper Albian, western Europe.
  • P. granulostriata (Desor, 1855); Turonian, western Europe.
  • P. vendociniensis (Agassiz & Desor, 1847); Turonian-Santonian, western Europe.
  • P. pseudopistillum (Cotteau, 1862); Santonian, western Europe.
  • P. arnaudi (Lambert, 1909); Campanian-Maastrichtian, western Europe.
  • P. subvenulosa (Peron & Gauthier, 1880); Turonian, Algeria.
Classification and/or Status

Cidaroida, Cidaridae, Cidarinae.



The tall test with its closely spaced interambulacral primary tubercles with confluent scrobicular circles, subconjugate pore-pairs and the finely thorned spines help distinguish this genus.

Agassiz, A. 1863. List of echinoderms sent to different institutions in exchange for other specimens. Bulletin of the Museum of Comparative Zoology, Harvard College, 1 (2), 17-28.

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.

Smith, A. B. & Wright, C. W. 1989. British Cretaceous Echinoids. Pasrt 1, general introduction and the Cidaroida. Monograph of the Palaeontographical Society, London publication 578, 1-101, pls 1-32.